Method of purification of polymerized rosins and rosin esters



Patented Oct. 27, 1942 UNITED METHOD OF PURIFICATION OF POLYMER- IZED ROSINS AND BOSIN ESTEBIS Alfred I. Bummelsburs, Wilmington, M, assigns: to Hercules Powder Company, Wilmington, Del., a corporation of Delaware No Drawing. Application December 27, 1940, Serial No. 371,990

11 Claims. (01. 200-91) a This invention relates to the purification of polymerized rosins and rosin esters and more particularly to an improved method of purifying polymerized rosins or rosin esters which have been polymerized by means of strong polybasic mineral acid or organic substituted polybasic mineral acid catalysts.

In the polymerization of rosins and rosin esters with acid catalysts such as strong polybasic mineral acids and organic substituted polybasic mineral acids it is necessary-to remove the catalyst from the polymerized product in the purification thereof. The presence of even small amounts of the acid catalyst in the final product leads tostitution products thereof, exhibit a tendency to form addition products at the unsaturated bonds of the rosin material. Thus in the case of sulfuric acid an addition product corresponding to a sulfate is formed. The presence of-such addition products in the polymerized mixture seriously handicaps the washingoperation for removal of the acid. They behave as emulsifying agents during a washing procedure and therefore make it very difllcult and in some cases impossible to eflect a separation between the water layer and the solvent solution of the polymerized rosin or rosin ester. The emulsions which they form require long periods of standing before they break and thereby considerably lengthen the time required for the washing operation as well as materially reducing the effective separation of the polymerized material from the wash solution. In the commercial production of polymerized rosin or rosin esters utilizing as catalysts such strong polybasic mineral acids as form the addition prodnot with the rosin or rosin ester, the formation of emulsions in the washing operation has been a factor of such severity as to seriously handicap the production. 4

It is an object of this invention to provide an improved method of purification of polymerized rosins or rosin esters which have been polymerized by use of strong polybasic mineral acid or organic substituted polybasic mineral acid catalysts. It is a further object to provide an improved and more efiicient means or removing catalyst from polymerized rosins or rosin esters which have been polymerized by means of strong polybasic mineral acids or organic substituted polybasic mineral acids. It is a more particular object to provide an improved and more emcient means of removing sulfuric acid from a polymerized rosin or rosin ester which has beeri'polymerized by means of this acid as a catalyst.\ Other objects of the invention will appear hereinafter'.

The above objects are accomplished in accordance with this invention by subjecting a polymerized rosin or rosin ester which has been polymerized by means of a strong polybasic mineral acid or organic substituted polybasic mineral acid prior to a water washing step to a hydrolysis treatment with an aqueous solution of an inorganic acid at a temperature which is sufficient to effect substantially complete hydrolysis of any addition product formed bycombination of the polymerization catalyst with the rosin or rosin ester material. on completion of the hydrolysistreatment the acid solution is removed and the polymerized rosin or rosin ester solution washed with water to substantially completely remove the polymerizing acid and the acid used in the hydrolysis treatment. As a direct result of the hydrolysis treatment the water washing step is ac complished without appreciable emulsion formation and a clean separation is easily eflected. A materially simplified procedure and an improved yield of polymerized product is thereby obtained. In addition, a polymerized product substantially completely free of traces of the polymerizing acid is made possible. This isof particular importance in relation to used sulfuric acid since sulfur contamination in even very small amounts has an adverse eilect.

The hydrolysis treatment described in accordance with this invention may be applied to the products obtained by polymerization or any or the various grades of rosin or any ofthe various rosin esters obtained by contact with a strong polybasic mineral acid or an organic substitutedpolybasic mineral acid as polymerization catalyst. Thus the hydrolysis treatment may be applied to the various grades of either wood or gum rosin or to esters of such rosins as for example the methyl, ethyl, propyl, butyl, ethylene glycol, diethylene glycol, glycerol, pentaerythritol, etc. esters, which have been polymerized by contact with polymerization catalysts such as for examplesulfuric acid, phosphoric acid, tetraphosphoric acid, methyl sulfuric acid, ethyl sulfuric acid,.-

acetyl sulfuric acid, acetyl phosphoric acid. ethyl suiilu'ic acid, benzyl sulfuric acid, etc. The poly= merization of resins and rosin esters with such catalysts is usually carried out on the rosin or rosin ester dissolved in a suitable organic solvent such as for example gasoline, benzene, toluene, cyclohexane, chloroform, ethylene dichloride, dichioroethyl ether, tetrachloroethane, decahydronapthalene, etc.

The inorganic acids which may be used in the form of aqueous solutions thereof in the hy droiysis treatment may be the particular acid used' in the polymerization treatment and thus may include any of the above enumerated acids. In addition, aqueous solutions of acids such as hydrochloric, nitric, boric, etc. or acid salts which provide an acid reaction in aqueous medium such as sodium acid sulfate, sodium acid phosphate, etc. may be employed. The concentration of the aqueous solution of the. hydrolyzing acid may vary up to as high as 60% by weight and may even be as low as 1% by weight, or in some cases even lower. Preferably the concentration oi the hydrolyzing acid will be in. the range of about 5% to about 50% by weight. The amount oi the aqueous solution oi inorganic acid used in the hydrolysis treatment may vary over wide ranges and will include amounts from about to about 10 times the volume of the polymerized rosin or rosin ester solution.

The timerequired to sheet satisfactory hyd'rolysis will depend to a certain extent on the concentration oi the hydrolyzing acid and on the temperature of treatment. It is usually messsary to employ temperatures above about 50 *3. to effect the desired hydrolysis, and temperatures up to as high as 200 C. are contemplated. When the temperature of hydrolysis is above the bulbing point of the solvent in which the polymer ized rosin "or rosin ester is dissolved the treat ment is carried out under pressure in a closed I i system such as an autoclave.

The time for car rying out the hydrolysis treatment may accordingly vary from about 5 minutes to about 5 hours, depending in any particular case on the temperature and the concentration of hydrolyzing acidfiemployed. Generally speaking the higher the temperature of hydrolysis the shorter the time required. Also, similarly, the more concentrated the acid solution employed the more rapid the hydrolysis.

The concentration or the acid employed in the hydrolyzing treatment is limited by the fact that certain inorganic acids efiect a degradation or a discoloration oi the polymerized rosin or rosin ester in the more concentrated forms in the ele= vated temperatures of treatment. However, it has been found that by using a concentration of acid not in excess. oi about 60% by weight and a temperature not above about il C. that substantially no degradation or discoloration of the Iifiblymerized material occurs. It has also been found that Within these limits substantially no hydrolysis of the ester group in polymerized rosin esters occurs, thereby making the donned process generally applicable to both polymerized resins and rosin esters. flhe use of an inert atmosphere during the hydrolysis treatment is contemplated since'by this means it is possible to avoid any color degradation of the polymerized materials. For this purpose the inert atmosphere may be provided by gases as carbondioxide, nitrogen, etc.

In the polymerization of rosin or rosin esters with acids such as concentrated sulfuric acid. a

arouses addition products of the sulfuric acid with the rosin material. Addition of water to such a heterogeneous polymerization mixture serves to break up such sludge and to divert the combined rosin into the organic solvent and the sulfuric acid into the acid layer. If desired, the sludge may be separated to facilitate production or a r lighter colored polymerized product. With such mixtures the hydrolysis treatment may be conveniently carried out by addition of sufdcient water to provide an aqueous acid layer containing up to about 60% of sulfuric acid and by heating the mixture with suitable agitation at a tern perature and for a time suincient to etect break-up oi any addition product of the acid with the rosin or rosin ester such as in the ranges defined above. furic acid and solvents such as benzene, toluene or gasoline but using a rosin concentration oi 60% or higher, homogeneous reaction mixtures are obtained which may be subjected to the hy== drolysis treatment directly or may be diluted with additional solvent to separate a sludge, and their hydrolyzed as above.

In the polymerization of resin or rosin esters with a polybasic mineral acid catalyst such as concentrated sulfuric acid using a solvent for the rosin or rosin ester which provides a homogene-ous reaction mixture at both low and high rosin concentrations such as, for example, ethylene dl= chloride, dichloroethyl other, tetrachloroethane, etc., addition 01' water may be made to provide an aqueous acid concentration of up to about 60% and the hydrolysis treatment carried out on such a mixture by heating as described above. if desired, additional acid may be adder; or tional aqueous solution of acid to provide larger amounts of aqueous acid for the hydrolysis treatment. 1

On completion of the hydrolysis treatment the aqueous acid used in the hydrolysis may be drawn off. from the polymerized rosin rosin ester solution and the polymerized subjected to successive washings with water to remove the last traces of acid. A small amount of a neutral salt such as sodium chloride may be included in the wash water to effect a more rapid separation of the two layers. lhus a 2.5% sodi= um chloride solution provides an efiective wash ing medium. The washing operation may be ei tected in considerably less time than is possible without the prior hydrolysis treatment and a more efficient separation of the polymerized rosin solution is obtained.

The above hydrolysis treatment provides par= ticularly desirable results when applied to sephomogeneous or a heterogeneous reaction. mix to aration oi polymerized rosin iromethe polymerized rosin sludge produced under certain condi= I With use of concentrated sul On completion of the washing procedure the henzone was evaporated to recover the polymerized rosin. The time required for separation of each wash solution and the analysis of each polymerized rosin are shown in Table 2 below.

- 9,800,065 3 Exmru: I Table 2 To a solution of 262 parts by weight of K wood rosin in 600 parts of benzene, '70 parts of 95% n drol a sulfuric acid were added with vigorous agitation fi during a period of about 12 minutes at a temperature of 11-15 C. Agitation was continued 7 i for 35 minutes at 15 0. and the mixture then 3$; allowed to stand another 15 minutes at 15 C. 15 mm The benzene solution was then decanted from 3min. the sludge. The benzene solution amounted to 15 ink, 520 parts and contained 1.2% of sulfuric acid. 3min.-

One hundred parts of water were then added Add g 153 154 giiiiig approximate llyha 9%tsolution of sulfuric MelgnlgpoiniIIIIII:IIIII: 0320 an 0. B in the water. is mix ure was heated with agitation under reflux at a temperature of 80 Pemntsuuu' M62 C. for one hour. The aqueous sulfuric acid solution was then drawn oil and the benzene solution Bath layers clouds" washed three consecutive times with 1000 part EXAMP E III portions of water at a temperature of 18-25 C. and permitting the mixture to stand after each 20 T0 3 Solution O 400 Parts of WG 8 r0611! wash until satisfactory separation could be efin 157 Parts Of r ow r nge gasoline having a fected. The procedure was duplicated with use boiling range 0195-130" cu .100 Parts of 85% of sodium chloride solution instead of water sulfuric acid were added with agitation over a in the washing. period of /2 hour maintaining the temperature A similar polymerization mixture was subj t 25 at -32 C. The homogeneous reaction mixture ed to a hydrolysis treatment at the same temobtained was agitated f0! 1% hours at the same perature and f r the same time but with use temperature and the reaction mixture then a 50% sulfuric acid solution. Washing was carpoured into 740 parts of the narrow range as rl d t, a above b t it and t t sodium line with agitation. The gasoline solution was chloride in the water. As a comparator to the so then Separated o e Sludge d divided t above two procedures a similar polymerization two equal Portions- The first was mixture was washed with water without the hyjected to hydrolysis treatment with 100 Parts drolysis treatment. The time in minutes re of 10% sulfuric acid at a temperature of quired for separation of each wash solution and n hour with agitatmn- The acid was the analysis of the polymerized rosin obtained then separated and the gasoline solution a t b t be1ow m Table 1, iected to three successive washes with 1000 part Table 1 portions of water containing 2.5% sodium chloride at a temperature of 18-25 C. Each wash solu- N H an an Si tion was shaken with the polymerized rosin -so- Y Y 0? s -lution for three minutes, allowed to stand and hywlysls 9% 11,80 the separation time then determined. The sec- 0nd portion of the polymerized rosin solution 20 min 1 min. was subjected to the same washing treatment but 1mm 1mm without being subjected to the hydrolysis pro- 15 min 15 min. cedure. Table 3 below shows the separation time in each case and the analysis of each polymerized 15 mln. l5min. rosin obtained. 1min.. 5min. Table 3 C l grad M 1 0 g5 Pgrgzntsufi'dEIII 0.021 0.00% 0.015. gf g $521522 1 Both layers hazy. First wash EXAMPLE II Second wash Third wash The polymerization procedure of Example I lg ggg was repeated but with use of a polymerization Melting bblil'tIIIIIIIIIIIIIIIIIII temperature oi 23-25" C. The polymerization gg lgg f gflf X tntiaixture without separation of the sludge was en subjected to a hy'drolysistreatment with 300 parts of 50% aqueous sulfuric acid with agid1at ffiefi'glfl'tifi ifig iifii finfi miitmifif tation under reflux at a temperature of about C. for one hour. The acid layer was then EXAMPLE Iv separated and the benzene solution of the polymerized rosin washed three successive times with 5 To a Solution of 300 pains K mm 1000 part portions of watch In a duplicate may in 560 parts of ethylene dichlorlde, 70 parts of aration the washing was carried out with water sulfuric were added with agitation over containing 25% sodium chmfldfl For purposes a period of 10 minutes while maintaining the of comparison a similar polymerization was cartemperature at The mixture was ried out but without the hydrolysis treatment. 70 agitated 1/2 m at temperature 18-20 C. To the homogeneous reaction mixture parts of water were then added with agitation over a period of 25 minutes, at a temperature of 23 'C., thereby diluting the sulfuric acid layer to approximately 30% concentration. The reaction e with the 30% acid dispersed therein was divided into two equal portions. The first portion was subjected to a hydrolysis treatment with 200. parts of 10% aqueous sulfuric acid solution for, one hour at a temperature of 80 C. The concentration of the hydrolysis acid was thus 20%. Aftercompletion of the hydrolysis treatment the polymerized rosin solution was subjected to three consecutive washes with 1000 part portions of water containing 2% sodium chloride. The second portion of the polymerized rosin solution was subjected to a similar washing procedure but without the hydrolysis treatment. The ethylene dichoride was evaporated from the washed solutions to provide the polymerized rosin. In Table 4 below the time required for each wash solution to separate after an agitation period of three minutes is shown together with the analysis of the polymerized rosin product.

Table 4 H dlrolysis 8 00 15 min. 1.5

1.5 min.

1 min.

i 130th layers EXAMPLE V To a solution of 300 parts of K wood rosin in 560 parts of benzene, 70 parts of 95% sulfuric acid were added with agitation over a period of 10 minutes maintaining a temperature of 20 C.

After continuing the agitation for an additional half hour at the same temperature, the reaction mixture was allowed to stand at 20 C. for another minutes. The benzene soiution'was and divided into two equal ortions. .The first portion was subjected to a hydrolysis treatment then separated from the sludge which formed v with 5.25 parts or 25% aqueous phosphoric acid solution by heating at 80 C. with agitation for one hour. The acid layer was then separated and the benzene solution washed three consecutive times with 1000 part portions of water containing 2.5% sodium chloride. The second portion was subjected to a similar washing procedure but without the hydrolysis treatment.

A similar polymerization to the above was carried out and the benzene solution again divided into two equal portions. One po tion was sub- Jected to a hydrolysis treatment with 500 parts oi 10% aqueous hydrochloric acid solution under the same conditions vas above. The second portion was subjected to a similar hydrolysis treatment but with 300 parts of 15% aqueous horic acid solution. Each solution was then subjected to a washing treatment similar to that employed above.

In Table 5 below the time required for separation of each wash-solution and the analysis or aeoaoes Table 5 Hydrol Hydrol Hydrol No hyg sis 25 sis l0 sis l5 drllysis an? 1 H01 H B l Firstwash l7min. 7min.-. 3 min..- 3 min. Scoundwash 20min. 4 min... 3 min 3min. Thirdwssh 45 min. 1.5 min 3 min 3.5min. Analysis of rosin 104 C.-- 104 C 102 C..- 103 C. Colorgrade K I H K. Percent sulfur 0.028.-.. 0.007-... 0.007-. 0.012.

1 Both layers milky.

EXAMFLE VI To a solution of 300' parts of a glycerol ester of wood rosin in 500 parts of benzene, 100 parts of 95% sulfuric acid were added with agitation over a period of 20 minutes while maintaining the temperature at 15-20 C. Agitation of the mixture was continued for 1%, hours at the same temperature, the sludge then allowed to settle and the benzene solution decanted therefrom and divided into two equal portions. The first portion wessubjected to a hydrolysis treatment with 200 parts of 15% aqueous sulfuric acid solution for 5 hours at a temperature of 80 C. After separation of the acid the benzene solution was washed three successive times with 1000 part portions of water containing 2.5% sodium chloride. The second portion was subjected to the washing treatment without hydrolysis. In Table 6 below the time required for separation of each wash solution and the analysis of the ester after evaporation of the solvent are given.

Table 6 No Hydrolysis hydrolysis 15% H 80 00 min. 5 min.

120 min. 10 min 720 min. 10min.

ll6'-C 116 C.

1 Both layers cloudy.

EXAMPLE VII Four hundred parts of WG gum rosin were dissolved in 225 parts or narrow range gasoline (B. P. 200-270 F.) and the solution agitated for 4 hours with parts of tetraphosphoric acid under reflux at 8090 C. The reaction solution was then diluted with 515 parts of the narrow range gasoline with agitation, cooled to room temperature and allowed to stand for 15 minutes.-

' increased the separation time and which made tion of the solvent in each case are shown.

a clean separation difiicult. The second part oi. the polymerized rosin solution was agitated for one hour under reflux at -90 C. with 400 parts of a 25% sulfuric acid solution. After separation of the aqueous acid layer, the solution waswashed with three consecutive 1000 part portions the two polymerized rosin solutions yielded poly- I merized products having the following analyses:

The polymerized product obtained above was contaminated with oils formed during the polymerization. By subjecting the product to.vacuum distillation at 1 mm. pressure 40% of oils and unpolymerized rosin were distilled off. The residual polymerized rosin had an acid number of 163 and a drop melting point of 100 C.

It will be readily apparent from the above examples that the hydrolysis treatment described in accordance with this invention makes it possible to remove acid catalysts from polymerized resin or rosin ester solutions in a much more eflicient manner. Thus the examples illustrate that a cleaner separation and a more rapid separation of the wash solutions from the polymerized resin or rosin ester solutions is possible by subiecting the polymerized rosin or rosin ester solution to the described hydrolysis treatment prior to water washing. By use or such a hydrolysis procedure it is now possible to satisfactorily wash such polymerized rosin or rosin estersolutions conveniently and effectively to remove the last traces or acid catalyst therefrom. The hydrolysis treatment also makes it commercially practical to polymerize rosin with strong polybasic mineral acid catalysts. The hydrolysis treatment also makes it possible to produce a sulfuric acid polymerized rosin or rosin ester which will contain less-combined sulfur than has been possible by any previously lrnownpurification procedure.

Although the specific examples shown above illustrate the process of the invention in terms or a batch procedure it will be obvious that the hydrolysis treatment can also be carried out in a continuous manner, .for example by passing the polymerized rosin solutions and the hydrolyzing acid concurrently through a contact chamber or tube, or by passing the polymerized rosin solution up through the hydrolyzing acid, or by passing a solution 01- the polymerized rosin or rosin ester and the hydrolyzing acid countercurrently through any suitable device, as well as by other procedures which will be apparent to those skilled in the art. Also, the hydrolysis treatment may be included as a step in the continuous polymerization of resin by the process utilizing a suliuric acid sludge catalyst, such as is described in an application of Clell E. Tyler, Serial No. 328,864, filed April 10, 1940, and in an application or C. E. Tyler and W. N. Traylor, Serial No. 328,866, filed April 10, 1940.

It will be understood that the details and examples hereinbeiore set forth are illustrative only, and that the invention as herein broadly described and claimed is in no way limited thereby. I

What I claim and desire to protect by Letters Patent is:

1. In the polymerization of a material selected from the group consisting of rosins and resin from the group consisting of strong polybasic mineral acids and acidic organic substituted polybasic mineral acids, the step in the purification which comprises hydrolyzing the polymerized material prior to water washing with an aqueous solution of an inorganic acid to effect substantially complete hydrolysis of any addition product formed by combination of the polymerization catalyst with the resin or rosin ester material.

2. In the polymerization of a material selected from the group consisting of rosins and rosin esters with a polymerization catalyst selected from the group consisting of strong polybasic mineral acids and acidic organic substituted polybasic mineral acids, the step in the purification which comprises hydrolyzing the polymerized material prior to water washing with an aqueous solution of an inorganic acid at a temperature within the range of about 50 C. to about 200 C. to efiect substantially complete hydrolysis of any addition product formed by combination oi. the polymerization catalyst with the rosin or rosin ester material.

3. In the polymerization of a material selected from the group consisting of resins and rosin esters with a polymerization catalyst selected from the group consisting of strong polybasic mineral acids and acidic organic substituted polybasic mineral acids, the step in the purification which comprises hydrolyzing the polymerized material prior to water washing with an aqueous solution of an inorganic acid having a concentration up to about 60 per cent by weight at a temperature within the range of about 50 C. to about 200C. to effect substantially complete hydrolysis of any addition product formed by combination of the polymerization catalyst with the resin or rosin ester material.

4. In the polymerization of rosin with a polymerization catalyst selected from the group consisting of strong polybasic mineral acids and acidic organic substituted polybasic mineral acids, the step in the purification which comprises hydrolyzing the polymerized rosin prior to water washing with an aqueous solution or an inorganic acid having a concentrationup to about per cent by weight at a temperature within the range of about 50 C. to about 200 C. to etiect substantially complete hydrolysis of any addition product formed by combination of the polymerization catalyst with the rosin or rosin ester.

5. In the polymerization of rosin with sulfuric acid as a polymerization catalyst, the step in the purification which comprises hydrolyzing the polymerized rosin prior to water washing with an aqueous solution of an inorganic acid having a concentration up to about 60 per cent esters with a polymerization catalyst selected by weight at a temperature within the range of about 50 C. to about 200 C. for a sufiicient time to eflect substantially complete hydrolysis of any addition product formed by combination of the sulfuric acid with the rosin material.

6. In the polymerization of rosin with phosphoric acid as a polymerization catalyst, the step in the purification which comprises hydrolyzing the polymerized rosin prior to water washing with an aqueous solution or an inorganic acid having a concentration up to about 60 per cent by weight at a temperature within the range of about 50 C. to about 200 C. for a sufilcient time to effect substantially complete hydrolysis of any addition product formed by combination or the phosphoric acid with the rosin material. 

